1. Field of the Invention
The invention relates to a writing tube pen tip having a pen body comprising a tube pen in its tip and a drop weight body, in the front section of which is disposed a cleaning wire extending into the tube pen.
2. Brief Description of the Prior Art
Such writing tube pen tips are known in various embodiments (e.g., German Patent 1 911 951 and German published application DE-OS 30 09 100). Generally the rear section of the pen body forms an inner bore, into which the drop weight is inserted. The drop weight is limited in its back and forth movement so that the cleaning wire, which in its position of rest slightly protrudes over the front end of the tube pen, can shift axially backwards when the front end of the tube pen is placed on a writing or drawing surface. This motion causes the front end of the writing tube to come into flat contact with the writing surface.
The back of the inner bore is connected with a writing fluid storage chamber, such as an interchangeable ink cartridge, and a pressure equalization chamber is disposed between the exterior wall of the pen body and a covering tubular body. The pressure equalization chamber is connected with the inner bore on the one hand and with the ambient air on the other.
Writing tube tips of this type are used as parts of tube pens which are employed as manual drawing devices as well as with plotters, where a plotter pen is inserted into a holder that is moved across a drawing or writing surface, in a controlled manner.
As mentioned above, the front end of a writing tube is in flat contact with a writing or drawing surface during operation of the known tube pen tips. This fact limits the drawing speed of such tube pen tips for the reason that above a certain drawing speed it is impossible to apply a sufficient amount of drawing fluid to the surface from a writing tube that is in flat contact with the writing or drawing surface.